On parametric evenness measures.

The degree to which abundances are divided equitably among community species or evenness is a basic property of any biological community. Several evenness indices have thus far been proposed in ecological literature. However, despite its vast potential applicability in ecological research, none seems to be generally preferred. Furthermore, only very few parametric evenness families have thus far been proposed. While traditional evenness indices supply point descriptions of community evenness, according to a parametric evenness family E(alpha), there is a continuum of possible evenness measures that differ in their sensitivity to changes in the relative abundances of dominant and rare species as a function of the parameter alpha. In this review, I first summarize the basic requirements that a parametric evenness measure should meet to adequately behave in ecological studies. Next, I discuss the major drawbacks of these requirements and propose some alternative solutions.